1. Field of the Invention
The present invention relates to a control circuit for a telephone system, and more particularly to a circuit for controlling visual and audible signals at the subscriber stations of a private branch exchange.
2. The Prior Art
Arrangements for the switching on of visual and audible signals at subscriber stations in private branch exchanges such as in hotel telephone systems, is known. Typically, the audible signals are produced by connecting an AC signal to the telephone transmission line, and a visual signal is produced by connecting DC to the transmission line. Such arrangements, however, require special line circuits or special external equipment and therefore involve substantial increased costs when added to a telephone communications system.